Method for the production of an illumination device and illumination device

ABSTRACT

The luminous area of a lighting apparatus  10, 110, 210  with a rectangular luminous area is made up in modular fashion from individual rectangular luminous modules  1 . The basic set comprises a first luminous module  11  of a first size, a second luminous module  21  of a second size, a third luminous module  31 , whose length corresponds to the length of the first luminous module  11  and whose width corresponds to the width of the second luminous module  21 , and a fourth luminous module  41 , whose length corresponds to the width of the first luminous module  11  and whose width corresponds to the length of the second luminous module  21 . By combining the luminous modules it is possible to produce backlighting for a multiplicity of display sizes.

RELATED APPLICATIONS

This is a U.S. national stage of application No. PCT/DE2004/000670,filed on Mar. 31, 2004.

This patent application claims the priority of German patent application103 14 525.7 filed Mar. 31, 2003, the disclosure content of which ishereby incorporated by reference.

FIELD OF THE INVENTION

The invention relates to a method for producing a lighting apparatuswith a polygonal luminous area, particularly a backlighting apparatusfor a display.

BACKGROUND OF THE INVENTION

Displays, for example for monitors, need to be backlit when using liquidcrystal displays, which themselves do not light up. This is normallydone using cold cathode lamps or, within the realms of miniaturizationand the production of flat screens, two-dimensional optical lightguides. Two-dimensional optical light guides as luminous areas areusually made of glass and are supplied with light, for example by lightemitting diodes (LEDs), at the side areas. Particularly from display andhence luminous area sizes having a screen diagonal with a length of 17″,the problem arises that homogeneous illumination of the entire area isnot or barely possible. Particularly in the center of the display, theillumination is weaker than in the rest of the screen. In addition, withconventional production facilities for lighting apparatus, it is acomplex matter to produce lighting apparatus in different sizes. Theproduction of two-dimensional lighting apparatus is a further difficultyas size increases.

SUMMARY OF THE INVENTION

One object of the invention is to provide a lighting apparatus whichovercomes the cited drawbacks of the prior art.

Another object of the invention is to provide a lighting apparatus whichcan be used to illuminate screens with a screen diagonal of over 17″very homogeneously.

Another object of the present invention is to provide a method that canbe used to produce lighting apparatus of different sizes flexibly.

A further object of the present invention is to facilitate production oflarge-area lighting apparatus.

These and other objects are attained in accordance with one aspect ofthe present invention directed to a method for producing a lightingapparatus that involves a polygonal luminous area, particularly abacklighting apparatus for a display. The luminous area is put togetherin modular fashion from a plurality of individual polygonal luminousmodules.

By combining a plurality of luminous modules of the same or differentsize it is possible to produce backlighting for a multiplicity ofdisplay sizes.

One approach for producing a lighting apparatus involves a rectangularluminous area being put together in modular fashion from a plurality ofindividual rectangular luminous modules.

In one preferred variant, the luminous modules are selected from a basicset of different-sized, preferably rectangular luminous modules. Such abasic set contains, so to speak, a basic kit containing luminous modulesin a limited number of different sizes. This allows a multiplicity ofdifferent-sized lighting apparatus to be put together using luminousmodules from the same basic set. This simplifies flexible production atlow cost.

If a nonrectangular luminous area needs to be created, it is naturallyalso possible to choose luminous modules with a different geometry, forexample luminous modules in the form of a non-orthogonal parallelogram.This special form of luminous modules could be used to backlight adisplay in the form of a non-orthogonal parallelogram, for example.

In one particularly preferred variant of the method, at least some ofthe plurality of luminous modules has a light input part with lightemitting diodes (LEDs). In contrast to a conventional lighting apparatuscomprising a single electroluminous panel, the invention can be used toachieve a more homogeneous distribution of the power loss and hence ofthe resultant heat over the entire lighting apparatus, since the LEDsare arranged not only at the edge of the luminous area but also withinthe luminous area at the junction between individual luminous modules.The light input part is in a form such that the light beams pass througha certain section within the light input part before entering theluminous module, whose top side is bounded by the light exit area. Inthis case, the light input part's area is not part of the light exitarea, whose size is denoted by the length of its diagonal in the case ofthe first and second luminous modules.

Other, preferably rod-like light sources, for example cold cathode lampssuch as CCFLs (Cold Cathode Fluorescent Lamp) or neon tubes, may also beprovided in the light input part within the context of the invention.Furthermore, it is also possible to use organic light sources such asOLEDs or electroluminescent films in this case.

In one preferred variant of the method, the basic set comprises a firstluminous module of a first size, a second luminous module of a secondsize, a third luminous module, whose length corresponds to the length ofthe first luminous module (11) and whose width corresponds to the widthof the second luminous module (21), and a fourth luminous module, whoselength corresponds to the width of the first luminous module (11) andwhose width corresponds to the length of the second luminous module(21).

In one particularly preferred variant of the method for producing alighting apparatus with a rectangular luminous area, the basic set ofluminous modules comprises four different-sized luminous modules, where

-   -   the length of the diagonal of a first luminous module is an        integer multiple of one inch and the ratio of length to width of        the luminous module is preferably 4:3,    -   the length of the diagonal of a second luminous module, which is        smaller than the first luminous module, is an integer multiple        of one inch and the ratio of length to width of the luminous        module is preferably 4:3,    -   the length of a third luminous module corresponds to the length        of the first luminous module and the width of the third luminous        module corresponds to the width of the second luminous module,        and    -   the length of a fourth luminous module corresponds to the width        of the first luminous module and the width of the fourth        luminous module corresponds to the length of the second luminous        module.

It is thus possible to produce a rectangular luminous area whosediagonal has an integer length measured in inches by arranging one ormore first and/or second luminous modules, which themselves have adiagonal whose length has an integer length in inches, along theluminous area diagonal, with the two luminous modules touching at thecorners. The remaining area of the rectangular luminous area is filledwith other luminous modules selected from the set of first, second,third and fourth luminous modules. A very small kit-like set of justfour luminous modules can thus be used to produce a multiplicity oflighting apparatus with different-sized luminous areas.

In one particularly preferred variant of the method, the length of thediagonal of the first luminous module is 7″ and the length of thediagonal of the second luminous module is 5″. These two luminous modulesand the resultant third and fourth luminous modules can be used toproduce lighting apparatus which are suitable for backlighting allcurrent monitor sizes. In this preferred variant, the third luminousmodule has length and width dimensions of 5.6″×3″ and the fourthluminous module has length and width dimensions of 4.2″×4″. Inparticular, this basic set can be used to produce lighting apparatus formonitors with a screen diagonal of 15, 17 and 19″.

However, lighting modules of other sizes may, of course, also be used asthe basic set, for example a first lighting module and a second lightingmodule which have the diagonal lengths 3″ and 4″. 4″ and 5″ or 3″ and 5″are other possible combinations. However, since the aim is to achievethe highest possible level of mechanical robustness for the entireluminous area while simultaneously reducing production complexity, it isadvantageous if the individual luminous modules are not chosen to be toosmall. If a basic set of luminous modules whose first or second luminousmodule has a diagonal length which is greater than 7″ or 5″ is used thenit is true that the mechanical robustness of the entire luminous areaincreases and the production complexity decreases, particularly in thecase of very large luminous area sizes. However, the number of possible,different-sized luminous areas which can be put together from such abasic set within the context of the available display sizes decreases.For special applications, it is also possible to imagine such luminousmodule sizes.

In one particularly preferred variant of the method, all of the luminousmodules have a light input part with light emitting diodes. This has theadvantage that a very homogeneous light emitting luminous area isattained without any great additional production complexity, primarilyby joining together the individual luminous modules.

In one preferred method, more or less all of the external areas of theluminous modules through which light is not intended to pass duringoperation are provided with a reflective coating. The coating thuscovers, in particular, the base area, the side areas and the part of thesurface of the light input part on which no LEDs are fitted. The lightexit area and the light entry area between the LEDs and the light inputpart are not coated

In one particularly preferred variant of the inventive method, aluminous body of the luminous modules is provided whose cross sectiontapers as the distance from the light input part increases. The effectachieved by the light exit area and the base area of the luminousmodules converging toward the end region is that the light supplied inthe light input part by the LEDs largely does not pass through theluminous module to the end region without emerging from the luminousmodule on account of total reflection. Instead, the tapering shape ofthe luminous module contributes to the light produced in the LEDsemerging almost totally homogeneously on the entire light exit area ofthe luminous modules.

In one particularly preferred variant of the inventive method, theindividual luminous body are in a form such that the thickness of theluminous body next to the light input part is greater than the thicknessof the light input part. As a result, a step is produced between thelight input part and the light exit area of the luminous module and canhave an adjacent luminous module engage in it, so that the luminousmodules can overlap, when put together to form a luminous area, suchthat light input parts which are situated below the luminous area arecovered. The effect achieved by this is that the total area of therectangular luminous area of the lighting apparatus actually correspondsto the sum of the areas of the individual luminous modules, and theluminous area formed by the light exit areas of the individual luminousmodules is largely planar.

In one preferred variant of the method, a luminous module has a basearea, which is opposite the light exit area, and a reflective structure,which directs light emitted by the LEDs during operation into the regionof the step. This achieves sufficient illumination in the region of thestep in a simple manner.

Another aspect of the present invention is directed to a lightingapparatus with a polygonal luminous area, particularly a backlightingapparatus for a display. The luminous area is made up in modular fashionfrom individual polygonal luminous modules.

A lighting apparatus based on an embodiment of the invention is made upfrom a plurality of individual luminous modules comprising a completebasic set or from a single type of luminous modules. The luminousmodules need to be put together such that a rectangular luminous areawith a length-to-width ratio of 4:3 and an integer diagonal measured ininches is obtained.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic illustration of a plan view of a first lightingapparatus,

FIG. 2 shows a schematic illustration of a plan view of a secondlighting apparatus,

FIG. 3 shows a schematic illustration of a plan view of a third lightingapparatus,

FIG. 4 shows a schematic illustration of a cross section through a firstluminous module,

FIG. 5 shows a schematic illustration of a cross section through afurther luminous module.

FIG. 6 shows a schematic illustration of a cross section through twojoined luminous modules.

DETAILED DESCRIPTION OF THE DRAWINGS.

Exemplary Embodiment 1 (FIG. 1):

This is a lighting apparatus 10 which has a plurality of luminousmodules 1 with a diagonal length of 5″. By putting together 3×3 luminousmodules 21 of this size, the result is a lighting apparatus 10 which hasa diagonal length of 15″. With a conventional electroluminescent panelof this size, it is difficult to achieve homogeneous illumination in thecenter of the luminous area. The effect achieved by using a plurality ofindividual smaller luminous modules 1 is that very homogeneousillumination is produced on the entire area of the rectangular luminousarea. In this exemplary embodiment, a single type 21 of luminous modulesfrom the set comprising 5″, 7″ and associated third and fourth luminousmodules has been selected from a basic set of luminous modules.

Using a basic set containing 3″ and 4″ luminous modules as first andsecond luminous modules, the same lighting apparatus would be attainedby putting together five times five 3″ modules.

The same number of rows and columns in a luminous area means that whenusing luminous modules with a length-to-width ratio of 4:3 and aninteger diagonal measured in inches there is always a rectangularluminous area with a length-to-width ratio of 4:3 and an integerdiagonal measured in inches.

Exemplary Embodiment 2 (FIG. 2):

This is a lighting apparatus 110 whose luminous area is made up of fourdifferent-sized luminous modules 11, 21, 31, 41. In this Figure, it isalso possible to see how a basic set is defined. Two luminous modules11, 21, whose light exit area has a diagonal length of 7″ or 5″ for alength-to-width ratio of 4:3, touch at one corner such that they can beinscribed in a rectangle with the diagonal length 12″. The two remainingrectangles 31, 41 for complementing the 12″ rectangle are obtained suchthat the length of the third luminous module 31 corresponds to thelength of the first luminous module 11 and the width of the thirdluminous module 31 corresponds to the width of the second luminousmodule 21, and the length of the fourth luminous module 41 correspondsto the width of the first luminous module 11 and the width of the fourthluminous module 41 corresponds to the length of the second luminousmodule 21. The dimensions 5.6″×3″ and 4.2″×4″ are thus obtained for thethird and fourth luminous modules.

Exemplary Embodiment 3 (FIG. 3):

This is a lighting apparatus 210 whose luminous area is made up of 9luminous modules containing four different-sized luminous modules. Thesame basic set as can be seen in FIG. 2 and containing just fourdifferent luminous modules 11, 21, 31, 41 is sufficient in order to puttogether such a luminous area. The diagonal length of 17″ obtainedcorresponds to commercially available screen sizes. The basic set usedhere can be used to put together luminous areas with diagonal lengths of10″, 14″, 15″, 19″, 20″, 21″ and 22″, for example. From a diagonallength of 24″ upwards, all integer lengths measured in inches arepossible.

Exemplary Embodiment 4 (FIG. 4):

This is a luminous module 1 which can be produced in various sizes andwhich is equipped with LEDs which input light into the luminous module 1at an end face of the light input part 3.

The tapering cross section of the luminous body 9 ensures that lightemerges over the entire light exit area because the light from the LEDsimpinges on the backside of the luminous body which is at an angle tothe front side. As a result, the light is bent to the front sidehomogeneously over the width of the lighting apparatus.

All of the areas through which, in contrast to the light exit area 6 andthe light entry area 16 between the LEDs and the light input part light,no light has to pass during operation are preferably provided with areflective coating 13 which prevent crosstalk between the luminousmodules via side faces and reduce losses.

A reflective structure 5 on the base area 4 between the light input part3 and the luminous body 9 helps light to pass directly behind the step 4to the light exit area through reflection. The reflective structure maybe in rippled form, for example. Any other structure which helps toavoid weaker illumination of the luminous body in the region of the stepis also suitable, however.

FIG. 4 shows that the end region 8 of the luminous module has the samethickness as the height of the step 4. This ensures a planar luminousarea after a plurality of individual luminous modules has been joinedtogether, as can be seen by way of example in FIGS. 1 to 3.

Exemplary Embodiment 5 (FIG. 5):

This is a further luminous module 1. A fundamental difference from theluminous module which is described in exemplary embodiment 4 is that thelight is input into the light input part 3 via the base area 7 of theluminous module. To get the light to be input into the entire luminousmodule, the light input part 3 is in a form such that the side which isopposite the LEDs has the shape of a parabola. The light emitted by theLEDs 2 is deflected on this parabolic side into the luminous body 9 ofthe luminous module 1. The step 4 and the end region 8 of the luminousmodule are again of such a height or thickness that individual luminousmodules 1, 11, 21, 31, 41 can be joined together such that the result isa planar surface for the luminous area of the lighting apparatus.

Exemplary Embodiment 6 (FIG. 6):

This shows an example of how two luminous modules (1) overlap, when puttogether to form a luminous area, such that the light input part 3 iscovered by the adjacent luminous module. The result is a largely planarluminous area.

The invention is not limited by the description with reference to theexemplary embodiments. Rather, the invention covers any new feature andany combination of features, which includes any combination of featuresin the patent claims, in particular, even if this feature or thiscombination itself is not explicitly indicated in the patent claims orexemplary embodiments.

The invention also extends to all methods and lighting apparatus whichhave the basic features of the invention. In particular, it may be usedfor lighting apparatus which are not based on the standard of an areadiagonal which has an integer length measured in inches. Other standardsfor illuminated objects, such as monitors, which are prescribed by themarket may require different dimensions for luminous areas, and hencefor individual luminous modules. The basic concept of the invention, touse a kit-like basic set of luminous modules, is not changed at all bythis. In addition, it is possible to use completely different geometriesthan rectangles for the luminous modules. In particular, triangles andhexagons are suitable for this. Such basic sets can be used to produce awhole series of luminous area shapes and sizes.

It is also possible to use a multiplicity of different LEDs which inputlight into the individual luminous modules. It is also possible tocombine various brightnesses and colors of individual LEDs. Allreflective materials, e.g. the conventional reflective materials, anddifferent materials may be used for the luminous bodies.

Finally, it is advantageous, but not absolutely necessary, within thecontext of the invention to use LEDs as light sources. Instead of LEDs,it is also possible to provide other light sources, preferably theaforementioned light sources such as cold cathode lamps in the form ofCCFLs or neon tubes, OLEDs or electroluminescent films.

The scope of protection of the invention is not limited to the examplesgiven hereinabove. The invention is embodied in each novelcharacteristic and each combination of characteristics, which includesevery combination of any features which are stated in the claims, evenif this combination of features is not explicitly stated in the claims.

The invention claimed is:
 1. A method for producing a display comprisinga backlighting apparatus, the backlighting apparatus having a polygonalluminous area which corresponds to a size of the display, the methodcomprising: assembling the polygonal luminous area of the backlightingapparatus in a modular manner from a plurality of individual polygonalluminous modules; and selecting the individual polygonal luminousmodules from a basic set of different-sized luminous modules; whereinthe basic set of different-sized luminous modules comprises: a firstluminous module having a first size, a second luminous module having asecond size, a third luminous module having a length that corresponds tothe length of the first luminous module and a width that corresponds tothe width of the second luminous module, and a fourth luminous modulehaving a length that corresponds to the width of the first luminousmodule and a width that corresponds to the length of the second luminousmodule, wherein each of said plural individual luminous modules has alight input part with light emitting diodes, wherein each of said pluralindividual luminous modules has a light exit area comprising a region ofa step, wherein a base area opposite the light exit area has areflective structure embodied as a rippled form which directs lightemitted by the light emitting diodes during operation into the region ofthe step.
 2. The method as claimed in claim 1, wherein the polygonalluminous area is rectangular and is modularly assembled from a pluralityof individual rectangular luminous modules.
 3. The method as claimed inclaim 1, wherein the basic set of different-sized luminous modulescomprises four different-sized luminous modules, wherein a length of adiagonal of the first luminous module is an integer multiple of 1 inchand a ratio of length to width of the first luminous module ispreferably 4:3, the length of the diagonal of the second luminousmodule, which is smaller than the diagonal length of the first luminousmodule, is an integer multiple of 1 inch and the ratio of length towidth of the second luminous module is preferably 4:3, the length of athird luminous module corresponds to the length of the first luminousmodule and the width of the third luminous module corresponds to thewidth of the second luminous module, and the length of a fourth luminousmodule corresponds to the width of the first luminous module and thewidth of the fourth luminous module corresponds to the length of thesecond luminous module.
 4. The method as claimed in claim 3, wherein thelength of the diagonal of the first luminous module is 7 inches and thelength of the diagonal of the second luminous module is 5 inches.
 5. Themethod as claimed in claim 1, wherein external areas of each of saidplural individual luminous modules, which are not one of a light exitarea and a light entry area, are at least partly provided with areflective coating.
 6. The method as claimed in claim 1, wherein aluminous body of each of said plural individual polygonal luminousmodules is provided whose cross section tapers as a distance from thelight input part increases.
 7. The method as claimed in claim 6, whereina thickness of the luminous body next to the light input part is greaterthan the thickness of the light input part, and the step located betweenthe light input part and the light exit area is in a form such that eachof said plural individual polygonal luminous modules overlap, whenassembled to form the polygonal luminous area, such that the light inputpart is covered by an adjacent luminous module.
 8. A display comprisinga backlighting apparatus, the backlighting apparatus having a polygonalluminous area, wherein the polygonal luminous area corresponds to a sizeof the display, wherein the polygonal luminous area comprises: aplurality of individual polygonal luminous modules arranged in modularmanner in the polygonal luminous area of the backlighting apparatus;wherein the individual polygonal luminous modules are selected from abasic set of different-sized luminous modules; wherein the basic set ofdifferent-sized luminous modules comprises: a first luminous modulehaving a first size, a second luminous module having a second size, athird luminous module having a length that corresponds to the length ofthe first luminous module and a width that corresponds to the width ofthe second luminous module, and a fourth luminous module having a lengththat corresponds to the width of the first luminous module and a widththat corresponds to the length of the second luminous module; andwherein the luminous area comprises one of each of said luminous modulesof the basic set of different-sized luminous modules or at least twopairs of luminous modules each having two different-sized luminousmodules in the basic set of different-sized luminous modules, whereineach of said plural individual luminous modules has a light input partwith light emitting diodes, wherein each of said plural individualluminous modules has a light exit area comprising a region of a step,and wherein a base area opposite the light exit area has a reflectivestructure embodied as a rippled form.
 9. The display as claimed in claim8, wherein the polygonal luminous area is rectangular and comprisesindividual rectangular luminous modules.
 10. The display as claimed inclaim 8, wherein the basic set of different-sized luminous modulescomprises four different-sized luminous modules, wherein a length of adiagonal of the first luminous module is an integer multiple of 1 inchand a ratio of length to width of the first luminous module ispreferably 4:3, the length of the diagonal of the second luminousmodule, which is smaller than the diagonal length of the first luminousmodule, is an integer multiple of 1 inch and the ratio of length towidth of the second luminous module is preferably 4:3, the length of thethird luminous module corresponds to the length of the first luminousmodule and the width of the third luminous module corresponds to thewidth of the second luminous module, and wherein the length of thefourth luminous module corresponds to the width of the first luminousmodule and the width of the fourth luminous module corresponds to thelength of the second luminous module.
 11. The display as claimed inclaim 10, wherein the length of the diagonal of the first luminousmodule is 7 inches and the length of the diagonal of the second luminousmodule is 5 inches.
 12. The display as claimed in claim 8, whereinexternal areas of each of said plural individual polygonal luminousmodules, which are not one of a light exit area and a light entry area,are at least partly provided with a reflective coating.
 13. The displayas claimed in claim 8, wherein a luminous body of each of said pluralindividual polygonal luminous modules is provided whose cross sectiontapers as a distance from the light input part increases.
 14. Thedisplay as claimed in claim 8, wherein a thickness of the luminous bodynext to the light input part is greater than the thickness of the lightinput part, with the step being in a form such that each of said pluralindividual polygonal luminous modules, when assembled form the polygonalluminous area, such that the light input part is covered by an adjacentluminous module.